Pushbutton switch with improved detent plunger retaining means



I y 1968 A. J. GARTLAND, JR 3,384,721

PUSHBUTTON SWITCH WITH IMPROVED DETENT PLUNGER RETAINING MEANS Filed Sept. 29, 1966 2 Sheets-Sheet 1 INVENTOR BY 2%W ATTORNEY y 1968 A. J. GARTLAND, JR 3,384,721

PUSHBUTTON SWITCH WITH IMPROVED DETENT PLUNGER RETAINING MEANS Filed Sept. 29, 1966 2 Sheets-Sheet .3

INVENTOR ATTORNEY United States Patent 3 384 721 PUSHBUTTON swrrcri wi'rrr IMPROVED DETENT PLUNGER RETAINING MEANS Albert II. Gartlaml, Jr., Trumbull, Conn., assignor to General Electric Company, a corporation of New York Filed Sept. 29, 1966, Ser. No. 583,008 4 Claims. (Cl. 200) ABSTRACT OF THE DISCLOSURE This invention relates generally to pushbutton switches, and more specifically to a slider type pushbutton switch incorporating a detent and detent support means.

Switches of the type having elongate sliders mounted in the hollow switch housing for reciprocation in response to digital manipulation of pushbuttons have achieved widespread application in the appliance industry. These switches are found, for example, in air conditioners, electric ranges, washing machines and dryers. A recent innovation in pushbutton switches is the provision of a detent which is incorporated in the switch structure in order to provide feel or initial resistance to finger pressure on the pushbuttons. This feel is necessary to ensure that the operator will follow through when pressing a pushbutton thereby to ensure that the switching operation of the switch will be completed. Further, the detent acts to retain the switch sliders in place against vibration such as is common, for example, in air conditioners, thereby preventing premature switching action and early failure of the switches.

A typical example of one such prior art detent may be seen in the US. patent to Stewart A. Woodward, 2,947,- 825'. Detents incorporated in such prior pushbutton switches of this type are supported by two or more of the standard sliders used in the switch, i e., the sliders used to actuate the switch contacts. The standard sliders are designed to provide a scissor-type action, wherein two or more inclined supporting sections located on separate sliders are located under the detent at all times. In this manner of providing detent support, it is necessary to include at least two standard sliders in each switch, and to design the switches so that at least two standard sliders move in opposite directions each time the switch is actuated to provide scissoring detent supporting action. Also, it has usually been necessary to provide one or more extra sliders in each detent bearing switch merely to furnish the scissoring action for supporting the detent, thereby nccessitating larger, more complicated switch structures and hence more expensive switch construction. Further, the scissor-like support provided by the standard sliders has proved to be generally unsatisfactory since the plunger portion of the detent often drops behind a supporting section of a slider causing the switch to lock-up and rendering the switch useless until it is taken apart and the condition remedied. This prior manner of supporting detent plungers also often fails to keep the plunger centered as it affords little or no lateral support for the plunger, leading to lock-up and often results in damage to the plunger itself. Also, the prior art slider supporting arrangement often leads to lock-up when e.g., all sliders shift to one side of the detent plunger as a result of shock or impact.

Patented May 21, 1968 Accordingly, it is a general object of the instant invention to provide a detent supporting means for pushbutton slider switches which solves at least some of the problems occurring in prior art detent bearing switches.

A more specific object of the present invention is to provide a detent guide or support means for use in pushbutton switches thereby achieving efiicient detent action while providing a less expensive, less complicated pushbutton switch.

In carrying out my invention, in one form, I apply it to a multiple pushbutton switch with a plurality of movable standard sliders. Each standard slider has a plurality of inclined working surfaces in one edge that are acted upon by pushrods, and a cam surface in the opposite edge for engaging movable contact supporting arms of the switch. Each standard slider also includes a detent actuating cam in the one edge for cooperating with a detent means incorporated in the switch housing. The detent means includes a plunger chamber which is perpendicularly oriented relative to, and opens into, a longitudinally extending slider chamber. A plunger is carried in the plunger chamber and is spring biased to a normal position wherein a forward or nose portion of the plunger extends outwardly of the detent chamber into the slider chamber for contact by the slider detent cams as the standard sliders are moved through the slider chamber. I provide a special member in the form of a stationary spacer or plunger supporting member generally shaped like the standard sliders. The plunger supporting member is mounted in the slider chamber, being positioned therein in-side-by-side relationship with the standard sliders. The plunger supporting member includes a supporting or cradle portion which provides the sole support for the detent plunger, restraining the plunger from any lateral movement, and limiting the plunger to vertical movement in the plunger chamber as the detent cams of the standard sliders make contact therewith. The plunger supporting member thereby frees the standard sliders from any plunger supporting function. The plunger supporting member has no working surfaces and hence remains stationary in the slider chamber, while the standard sliders move in response to depression of the pushbuttons. Accordingly, the cradle always remains in fixed supporting position with respect to the plunger.

My invention will be better understood from the following description taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims.

FIGURE 1 is a partial elevational view of a switch detent and the supporting arrangement therefor used in the prior art;

FIGURE 2 is a front elevational view, partially broken away and partially in section of a multiple pushbutton switch incorporating the detent supporting means comprising an aspect of the instant invention;

FIGURE 3 is a bottom plan view of the switch illustrated in FIGURE 2, with the cover plate removed in order to illustrate certain of the components thereof;

FIGURE 4 is a vertical sectional view taken substantially on the plane of the line 44 of FIGURE 2;

FIGURE 5 is a view similar to that of FIGURE 1 illustrating the manner in which a detent carried in a pushbutton switch is supported in accordance with my inven tion in one form; and

FIGURE 6 is a layout view of the sliders incorporated in the switch illustrated in FIGURES 24.

Referring now to the drawings in more detail, and especially to FIGURE 1, I have illustrated the prior art manner of providing detent plunger support in pushbutton switches incorporating detent means. FIGURE 1 shows, in partial elevation, a portion of a pushbutton switch 10 including the slider chamber 12 thereof, the

chamber 12 being closed by a cover plate 14. At least two standard sliders 16 and 18 are carried in the slider chamber 12, as at least two such standard sliders are necessary to provide support for the detent means which is generally denoted by reference numeral 20. The standard sliders include a plurality of inclined working surfaces 23 adapted for engagement by vertically movable pushrods (not illustrated) which move the standard sliders longitudinally through the slider chamber 12. The standard sliders also include cam surfaces for operating movable contact supporting arms (not illustrated). The detent means includes a spring biased plunger 22 vertically oriented with respect to the longitudinally extending slider chamber 12 and including a rounded nose or end portion 24 which extends into the chamber 12. It is necessary to provide support for the plunger 22 so as to prevent the biasing spring 26 from forcing it downwardly into the slider chamber 12. This support is provided, in the prior art arrangement illustrated in FIGURE 1, by detent cams or inclined supporting surfaces 28 on the two illustrated standard sliders which move to a position immediately below the plunger and scissor the nose portion 24 therebetween, or in other words grip the plunger restricting the vertical movement thereof. Of course, it will be understood that the conventional prior art pushbutton switch will include other standard sliders which have detent cams 28 which move past the plunger 22, forcing it upwardly against the force of the spring 26 to give the requisite feel that is provided by the detent means.

The supporting arrangement illustrated in FIGURE 1 is such that the inclined supporting surfaces or detent cams 28 of the standard sliders bear against opposite sides of the plunger 22 restraining any vertical movement of the plunger. Thus, it will be observed in FIGURE 1 that at least two standard sliders must be positioned so that their detent cams are immediately below the plunger 22. With such an arrangement it has usually been necessary in prior art switches to design the switch so that at least two standard sliders are moving in opposite directions for scissoring engagement with the plunger, and it therefore has usually been necessary to provide one or more extra standard sliders merely to furnish the requisite scissoring action. This, of course, necessitates larger, more complicated switch structures and therefore more expensive switch construction. Further, the plunger supporting arrangement has been generally unsatisfactory since there is little or no lateral or longitudinal support provided for the plunger during the movement of the standard sliders through the slider chamber 12, and hence the plunger 22 often drops behind the supporting detent cams 28 causing the switch to lock-up.

In accordance with the present invention, as illustrated in FIGURES 2-6 inclusive, I have provided an arrangement for supporting the detent plunger which obviates the problems occurring in the prior art. Referring first to FIGURES 2, 3, 4 and 5, I have illustrated therein a pushbutton switch 30 of generally standard configuration. The switch 30 includes a hollow housing 32 having the usual slider chamber 35 extending longitudinally therethrough. A plurality of pushrods 34 each having a pushbutton 36 mounted on the upper end thereof are mounted on the housing 30 for digital manipulation in accordance with the usual operation of pushbutton switches of this type. A back or cover plate 38 is removably mounted over an opening 40 in the bottom wall of the switch housing 30 in order to allow for assembly of the switch elements while also providing support therefor. These elements include fixed contacts 41 and movable switch contact arms 42 each carrying a contact 43 for engagement with the fixed contacts 41, and both of which are positioned in the switch housing adjacent the cover plate 38. The movable switch contact arms 42 are selectively engaged by cam surfaces 44 of movable standard sliders 46 in order to 4 selectively move the switch contacts 43 into and out of engagement with the fixed contacts 41 thereby completing circuits through the switch.

In accordance with one aspect of my invention, I provide detent means 48 in the switch housing in order to provide the digitally manipulatable pushrods 34 with a certain feel, and in order to lock the standard sliders 46 in place once they have passed the detent means 48. The detent means 48 includes a plunger chamber 50 having a longitudinal axis which is substantially perpendicular to the longitudinal axis of the longitudinally extending slider chamber 35. The plunger chamber 50 includes an entranceway 52 which opens into the slider chamber 35 and an enlarged recessed portion 54 surrounding and immediately adjacent the entranceway 52. Mounted in the plunger chamber 50 for reciprocal movement therein and vertical movement with respect to the longitudinally extending slider chamber 35 is a plunger 56. As will be observed particularly in FIGURE 5, the plunger 56 includes an enlarged forward portion 58 having a rounded nose or end 60 and a reduced rear portion 62 providing a shoulder 64. The plunger 56 is preferably constructed of a nylon material but may be constructed of any desirable rigid plastic material. A biasing spring 66 is provided for biasing the plunger 56 outwardly of the plunger chamber 50 in order to provide the required detent action for the switch. The spring 66 is a lightweight coil spring having the rear end located against the end wall of the plunger chamber 50 and the forward end received on the shoulder 64 of the detent 56. Thus, it will be understood that the spring 66 tends to bias or force the plunger 56 outwardly of the chamber 50.

In order to support the plunger 56 in accordance with the preferred aspect of my invention, I provide a plunger supporting means in the form of a plunger supporting spacer member generally denoted by reference numeral 68. The spacer member 68 is mounted in juxtaposed position in the slider chamber 35 between two of the standard sliders 46 as will be observed in FIGURES 3 and 4 for example. Further, by referring to FIGURE 6 it will be observed that the spacer member 68 does not have the inclined working surfaces 22 incorporated as a part of the standard sliders 46 for response to the pushrods 34, and hence the spacer member 68 remains stationary in the slider chamber 35 in contradistinction to the standard sliders 46. In this regard, the spacer member 68 includes generally U-shaped cutouts 70 in the upper edge thereof, the cutouts 70 having vertical edges rather than inclined working surfaces so that manipulation of the pushrods 34 does not move the spacer member 68. In further contradistinction to the standard sliders 46, which include cam surfaces 72 in the lower edge for engaging the movable switch contact arms 42, the spacer member 68 includes no such cam surfaces in its lower edge. T hus, it will be appreciated that the spacer member remains stationary in the slider chamber at all times and does not directly affect the switching operation of the switch.

It is necessary for the spacer member 68 to remain stationary in the slider chamber in order to provide support for the plunger 56. In this regard, the spacer member 68 includes a cradle portion 74 which extends slightly higher than the remaining upper edge of the member for engaging the detent plunger 56 in accordance with a preferred aspects of my invention. It will be noted, especially in FIGURES 2, 5 and 6 that the cradle portion 74 of the spacer member 68 includes a generally U-shaped cutout or notch 76 in the upper edge thereof which is permanently located below the plunger 56. The shape of the cutout or notch 76 is such that it conforms to the shape of the forward end 60 of the plunger 56 thereby surroundingly engaging this forward end thereof. The cradle thereby provides the sole support for the plunger, while constraining the plunger from any lateral or longitudinal movement in the direction of the longitudinal axis of the slider chamber 34 as the standard sliders 46 are moved therethrough.

At this point it may be well to briefly point out the manner of operation of the switch, which may best be appreciated by reference to FIGURES 2, 5 and 6 in particular, in order to appreciate some of the appreciable features achieved by my invention. Each standard slider 46, as mentioned above, includes inclined working surfaces 22 in the upper edge for engagement by the pushrods 34, and cam means 72 in the lower edge for operating the movable switch contact arms 42. As a pushrod 34 is depressed, as for example the pushrod 34a illustrated in FIGURE 6, the standard slider 46a will be moved to the left in response thereto, and the other pushrods 34 forced upwardly by their corresponding working surfaces. At this time, the movable switch contact blade 42a will be moved by the cam portion 72a of standard slider 46a out of engagement with its corresponding fixed contact 41. In order to retain the standard slider 46a in this actuated position, as well as to provide feel and follow through, the standard slider 46a, as well as the other standard sliders include detent cams 78 in the upper edge and generally at the center thereof. These detent earns 78 engage the forward or nose portion 60 of the detent plunger 56 as the standard sliders are moved through the slider chamber 35 forcing the plunger upwardly into the plunger chamber 50 as the detent cams 78 ride under the plunger 56. A function of the cradle 74 of the plunger supporting spacer member 68 is to provide support for the detent plunger 56 during its movement in response to the detent cams 78 of the various standard sliders 46. The support which is provided by the cradle 74 limits or constrains both the lateral movement of the plunger 56 due to the conformance of the plunger forward end 60 to the cutout or notch 75, and the vertical movement of the plunger as it rides up over the detent cams 78 and back downwardly into the plunger chamber 35. Thus, my plunger supporting spacer member 68 eliminates the possibility of the plunger 56 dropping behind a detent cam 78 and locking up the switch, and also eliminates the possibility of the plunger 56 moving laterally or longitudinally as it is engaged by a detent cam 78 and thus ensures a smooth detent action.

It will be appreciated that my new and improved detent support as herein illustrated provides an efficient and ad vantageous means for providing a detent action in a multiple pushbutton switch. It should be realized that while I have shown a single plunger supporting spacer member 68 located between several standard sliders in the slider chamber 35, it may be preferable to utilize any number of such plunger supporting spacer members 68, depending upon several factors, including the size of the switch and the number of standard sliders supported therein. In this regard, it may be preferable to include two plunger sup-porting spacer members such as the member 68 on opposite sides of the standard slider group to insure adequate support for the detent plunger 56.

While in accordance with the patent statutes, I have described what at present is considered to be the preferred embodiment of my invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from my invention, and I therefore aim in the following claims to cover all such equivalent variations as fall within the true spirit and scope of this invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A pushbutton switch including a hollow housing defining a longitudinally extending slider chamber; at least one slider mounted in said slider chamber for reciprocal movement therein; at least one movable switch contact mounted on said housing for actuation by said one slider; detent means for coacting with said one slider to releasably lock said one slider in either first or second positions;

said detent means including a plunger chamber in said housing opening into said slider chamber, and a plunger biasingly received in said plunger chamber for selective engagement with said at least one slider; and limiting means to limit the movement of said plunger out of said plunger chamber and for constraining the plunger from lateral movement, said limiting means including a stationary member having a generally U-shaped cutout to receive a portion of said plunger thereby to restrain said plunger from lateral movement as it is engaged by said one slider.

2. In a multiple pushbutton switch including a hollow housing forming a slider chamber, a plurality of contact means mounted on said housing, a plurality of pushbuttons mounted on said housing for digital actuation, a plurality of sliders mounted in said slider chamber for reciprocal movement in response to actuation of selected pushbuttons to operate said contact means, the improvement comprising, detent means mounted in said housing for selective engagement by said sliders to provide initial resistance to the movement of said sliders through said slider chamber, said detent means including a plunger having a portion extending into said slider chamber, spring means for urging said plunger to a first position, said plunger being retractable out of the path of said slider, and plunger supporting means mounted in said slider chamber for supporting said plunger when in the first position thereof and for limiting the lateral movement of said plunger as it is engaged by said sliders, said plunger supporting means including a spacer member mounted in said slider chamber in juxtaposed relationship with said sliders and being stationary with respect to said housing, said spacer member including a cradle portion including a generally U-shaped cutout surroundingly engaging a portion of said plunger extending into said slider chamber when said plunger is in its first position.

3. A pushbutton switch including a hollow housing defining a longitudinally extending slider chamber; at least one slider mounted in said slider chamber for reciprocal movement therein; at least one movable switch contact mounted on said housing for actuation by said one slider; detent means for coacting with said one slider to releasably lock said one slider in either first or second positions, said detent means including a plunger chamber in said housing opening into said slider chamber, and a plunger biasingly received in said plunger chamber of selective engagement with said at least one slider; and limiting means to limit the movement of said plunger means out of said plunger chamber and for constraining the plunger means for lateral movement, said limiting means comprising a plunger supporting spacer member mounted in said slider chamber in stationary relationship with respect to said housing, said spacer member including a cradle portion arranged adjacent the opening of said plunger chamher for supportingly receiving the forward end of said plunger, and a body portion being generally coextensive with said one slider.

4. The pushbutton switch of claim 3 wherein said cradle portion includes a generally U-shaped cutout for surroundingly receiving the forward end of said plunger thereby to restrain said plunger from lateral movement as it is engaged by said one slider.

References Cited UNITED STATES PATENTS 2,431,904 12/ 1947 Andrews 200-5 2,793,257 5/ 1957 Hutt 2005 2,810,027 10/ 1957 Woodward 200-5 2,947,825 8/ 1960 Woodward 2005 3,201,531 8/1965 Woodward 2005 ROBERT K. SCHAEFER, Primary Examiner.

J. R. SCOTT, Assistant Examiner. 

